Theresa May has been warned she will face a potential Tory rebellion if the Government “punishes” drivers of diesel vehicles when it publishes plans to improve air quality later this month.

Any attempt to make drivers “bear the burden” of the cost of bringing down pollution would trigger a backlash from MPs who fear “white van Conservatives” would turn their backs on the party, having been encouraged to buy diesels by the last Labour government.

Michael Gove, the Environment Secretary, has until the end of July to publish the Government’s long-awaited Air Quality Plan, which could include plans for a so-called “toxin tax” on diesel vehicles driving into cities.

The Government was ordered to do so by the High Court after missing a series of EU targets on air quality.